Carbomethoxy Group Research Articles

Exploring the Limits of Reactivity of N-Methyl-1,2,4-triazoline-3,5-dione (MeTAD) with Disubstituted Bicycloalkadienes in the Homo-Diels–Alder Reaction

The [2+2+2] cycloaddition (homo-Diels–Alder reaction) of N-substituted 1,2,4-triazoline-3,5-diones (TADs) with bicycloalkadienes produces strained heterocyclic compounds. A reaction with the unsubstituted dienes occurs readily to produce only the expected homo-Diels–Alder adducts. However, previous work in the literature showed that the attachment of a single electron-withdrawing group to the diene system results in the formation of not only the expected homo-Diels–Alder adducts, but also interesting “insertion” products. To probe the limits of reactivity of these diene systems, we investigated the reaction of N-methyl-1,2,4-triazoline-3,5-dione (MeTAD) with bicycloalkadienes substituted with two electron-withdrawing groups, i.e., two carbomethoxy or two cyano groups. We hoped to learn whether the reaction still proceeded, and if so, whether the homo-Diels–Alder adducts and/or other types of products were formed. We found that a reaction between MeTAD and the dienes takes place upon substitution with two carbomethoxy groups, albeit at a considerably slower rate than other reactions. The only products observed were the homo-Diels–Alder adducts. However, attachment of two CN groups completely inhibited reactivity.

Elucidating Instabilities Contributing to Capacity Fade in Bipyridine‐Based Materials for Non‐aqueous Flow Batteries

AbstractMetal‐based non‐aqueous redox flow batteries have the potential for long‐term energy storage if stability requirements can be achieved. One such stability issue in metal coordination complexes arises from ligand shedding in the anolyte upon reduction. Recognizing that the free ligands are relatively more stable than the metal coordination complex under highly reducing conditions, we evaluated a family of metal‐free bipyridinium materials as flow battery anolytes with the corresponding iron coordination complex as the catholyte. Bipyridinium compounds were functionalized for increased electrochemical stability, cycled in flow cells to understand efficiencies, and analyzed for degradation products. Methylation of the bipyridine nitrogens increased electrochemical stability yet left the reduced molecule susceptible to radical‐induced bond cleavage. Subsequent functionalization of bipyridine with carbomethoxy groups resulted in good battery performance with 96 % Coulombic and 90 % voltage efficiency, and improved cycling stability over a methoxy‐substituted anolyte with 14 % vs 36 % capacity fade in the first charge‐discharge cycle.

A novel structural type of conformationally fixed, mixed phosphonium-iodonium ylides based on phenoxaphosphinine

A synthetic approach to a novel type of phosphonium and mixed phosphonium-iodonium ylides containing a conformationally fixed phosphonium fragment is developed. New representatives of these families of chemical compounds based on cyclic phenoxaphosphinine were synthesized. One compound was structurally characterized by single-crystal X-ray diffraction. Based on the 1H NMR data, one can state that phosphonium ylide exists in solution in the form of two geometric isomers even at room temperature. This is indicative of pronounced double-bond character of the bond between the ylide carbon atom and the stabilizing carbomethoxy group.

A Biomimetic, One-Step Transformation of Simple Indolic Compounds to Malassezia-Related Alkaloids with High AhR Potency and Efficacy.

Malassezia furfur isolates from diseased skin preferentially biosynthesize compounds which are among the most active known aryl-hydrocarbon receptor (AhR) inducers, such as indirubin, tryptanthrin, indolo[3,2-b]carbazole, and 6-formylindolo[3,2-b]carbazole. In our effort to study their production from Malassezia spp., we investigated the role of indole-3-carbaldehyde (I3A), the most abundant metabolite of Malassezia when grown on tryptophan agar, as a possible starting material for the biosynthesis of the alkaloids. Treatment of I3A with H2O2 and use of catalysts like diphenyldiselenide resulted in the simultaneous one-step transformation of I3A to indirubin and tryptanthrin in good yields. The same reaction was first applied on simple indole and then on substituted indoles and indole-3-carbaldehydes, leading to a series of mono- and bisubstituted indirubins and tryptanthrins bearing halogens, alkyl, or carbomethoxy groups. Afterward, they were evaluated for their AhR agonist activity in recombinant human and mouse hepatoma cell lines containing a stably transfected AhR-response luciferase reporter gene. Among them, 3,9-dibromotryptanthrin was found to be equipotent to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as an AhR agonist, and 3-bromotryptanthrin was 10-times more potent than TCDD in the human HG2L7.5c1 cell line. In contrast, 3,9-dibromotryptanthrin and 3-bromotryptanthrin were ∼4000 and >10,000 times less potent than TCDD in the mouse H1L7.5c3 cell line, respectively, demonstrating that they are species-specific AhR agonists. Involvement of the AhR in the action of 3-bromotryptanthrin was confirmed by the ability of the AhR antagonists CH223191 and SR1 to inhibit 3-bromotryptanthrin-dependent reporter gene induction in human HG2L7.5c1 cells. In conclusion, I3A can be the starting material used by Malassezia for the production of both indirubin and tryptanthrin through an oxidation mechanism, and modification of these compounds can produce some highly potent, efficacious and species-selective AhR agonists.

Biosynthetically Inspired Transformation of Iboga to Monomeric Post-iboga Alkaloids

Summary Organisms have evolved to produce various natural products from a common precursor as a means of maximizing the number of secondary metabolites, thus acquiring selectional advantages. By adopting nature's divergent biosynthetic strategy, we transformed (+)-catharanthine to various iboga and post-iboga alkaloids, including (−)-conodusine A, (+)-conodusines B and C, (−)-voatinggine, (−)-tabertinggine, and (+)-dippinine B. Well-orchestrated oxidations and reorganizations of catharanthine derivatives enabled chemical access to these natural products.

A New Pathway for the Synthesis of a New Class of Blue Fluorescent Benzofuran Derivatives.

In this study an efficient and straightforward method for obtaining a new class of blue fluorescent bezofuran derivatives, under microwave irradiation, as well as under conventional thermal heating, is presented. Under conventional TH the reactions occur selectively, and a single type of benzofuran ester derivative was obtained. The synthesis under MW irradiation also led to benzofuran derivatives, but in a time-dependent manner. Irradiation for a short period of time led to a mixture of two types of benzofuran derivatives (3a–c and 4a–c), while MW irradiation for a longer period of time led to a single type of benzofuran (3-methylbenzofuran), the reaction becoming highly selective. Taking into consideration the advantages offered by MW irradiation in terms of a substantial decrease of solvent consumed, a substantial reduction in reaction time (from days to hours), and a consequent diminution in energy consumption, these methods could be considered environmentally friendly. Here, feasible reaction mechanisms for the benzofuran derivatives formation are described. The absorption and fluorescence emission of the obtained benzofuran derivatives were studied, with part of these compounds being intense blue emitters. A certain influence of the benzofuran substituents concerning absorption and fluorescent properties was observed. Only compounds anchored with a carbomethoxy group of furan ring have shown good quantum yields.

High Efficiency and Fast Removal of Trace Pb(II) from Aqueous Solution by Carbomethoxy-Functionalized Metal–Organic Framework

Lead (Pb) is one of the most widespread toxic heavy metals, and how to quickly and completely remove trace Pb(II) is a global concern. Herein, we prepared a novel metal-organic framework {[Cd(ADB)L2]∙1.5DMF∙2H2O}n (1) decorated with carbomethoxy groups and investigated the Pb(II) removal performance as well as the underlying mechanism. The MOF exhibits a fast kinetics with the kinetic rate constant k2 of 0.162 g mg-1 min-1, which is 1–3 orders of magnitude higher than the reported Pb(II) adsorbent materials. In addition, even in a concentration of 0.1 ppm, a high removal efficiency (96%) was still obtained after the treatment with the MOF and the concentration was reduced to 0.004 ppm, which is well below the drinking water standard of the World Health Organization (0.01 ppm). The possible adsorption mechanism was systematically verified by FT-IR and XPS investigations. The significant affinity between carbomethoxy groups and Pb(II) are responsible for the good removal performance.

Conformation and Visual Distinction between Urea and Thiourea Derivatives by an Acetate Ion and a Hexafluorosilicate Cocrystal of the Urea Derivative in the Detection of Water in Dimethylsulfoxide.

Structures of different solvates and solute–solvent interactions of 4-(3-(4-nitrophenyl)urido)benzoate (L1) and methyl-4-(3-(4-nitrophenyl)thiourido)benzoate (L2) with different solvents are analyzed. The solution of L1 with tetrabutylammonium acetate (TBAA) in dimethylsulfoxide (DMSO) is colorless, but a similar solution of L2 with TBAA is orange. On the other hand, respective solutions of these urea and thiourea derivatives with tetrabutylammonium fluoride (TBAF) in DMSO are orange. Urea derivative L1 facilitates the reaction of TBAF with glass to form tetrabutylammonium hexafluorosilicate, which on further interaction with L1 forms cocrystal 2L1·(TBA)2SiF6. Reorganization of hydrogen-bonded self-assembly of 2L1·(TBA)2SiF6 in DMSO caused by water is established by a dynamic light scattering study. With an increase in the amount of water in the solution, visual color changes from orange to colorless, and the color changes are reversed upon the addition of a dehydrating agent such as molecular sieves. Solvates of L1 with DMSO, dimethylformamide (DMF), and dimethylacetamide are quasi-isostructural. The respective self-assembly of these solvates differs due to orientations of aromatic rings and the carbomethoxy group across the thioamide/amide bond. Significant differences in self-assemblies of the respective DMSO solvate of L1 and L2 are observed; self-assembly of the former has dimeric subassemblies as repeat units, whereas the latter has monomeric subassemblies. DMF solvates of L1 and dimethylacetamide of L1 are built by dimeric subassemblies to form self-assembled structures, but these subassemblies differ in the orientation of the carbomethoxy group across the urea units.

Novel peptidylated surfaces for interference-free electrochemical detection of cardiac troponin I

Novel peptidylated surfaces were designed to minimise interferences when electrochemically detecting cardiac troponin I in complex biological samples. Disulfide-cored peptide dendrons featuring carbomethoxy groups were self-assembled on gold electrodes. The carbomethoxy groups were deprotected to obtain carboxylic groups used to immobilise antibodies for cardiac troponin I marker. The chemisorption of two types of peptides, one containing triazole and the other with native peptide bonds, on a gold substrate was studied by quartz crystal microbalance (QCM), surface plasmon resonance (SPR) and X-ray photoelectron spectroscopy (XPS). Peptides formed ordered self-assembled monolayers, contributing to a more efficient display of the subsequently immobilised antibodies towards their binding to the antigen. As a result, electrochemical immunosensors prepared by self-assembly of peptides afforded higher sensitivities for cardiac troponin I than those prepared by the chemisorption of alkane thiolated compounds. Triazolic peptide-modified immunosensors showed extraordinary sensitivity towards cardiac troponin I [1.7µA/(ng/mL) in phosphate buffer], but suffered from surface fouling in 10% serum. Modification with non-triazolic peptides gave rise to anti-fouling properties and still enabled the detection of cardiac troponin I at pg/mL concentrations in 10% serum without significant matrix effects.

Syntheses and Structures of Functionalized [9]Cycloparaphenylenes as Carbon Nanohoops Bearing Carbomethoxy and N-Phenylphthalimido Groups.

Functionalized [9]cycloparaphenylenes ([9]CPPs) bearing nine aromatic units in the macrocyclic structures were synthesized. The macrocyclic structures were substituted with carbomethoxy or N-phenylphthalimido groups. The Diels-Alder reaction of (E,E)-1,4-bis(4-bromophenyl)-1,3-butadiene or a related diene with dimethyl acetylenedicarboxylate followed by the nickel-mediated homocoupling reactions and oxidative aromatization produced the functionalized [9]CPPs. Treatment of a resultant [9]CPP with aniline or 1,4-diaminobenzene gave the corresponding N-phenylphthalimides. The X-ray structure of a [9]CPP bearing six carbomethoxy groups was obtained.

ChemInform Abstract: Intramolecular Cycloaddition Reactions of Furo[3,4‐b]indoles for Alkaloid Synthesis.

Model studies dealing with the Cu(II)- or Rh(II)-catalyzed carbenoid cyclization/cycloaddition cascade of several α-diazo indolo amido esters have been carried out as an approach to the alkaloid scandine. The Cu(II)-catalyzed reaction of an α-diazo indolo diester that contains a tethered oxa-pentenyl side chain was found to give rise to a reactive benzo[c]furan which undergoes a subsequent [4 + 2]-cycloaddition across the tethered π-bond. The reaction proceeds by the initial generation of a copper carbenoid intermediate which cyclizes onto the adjacent carbonyl group to give a reactive benzo[c]furan which in certain cases can be isolated. Disappointingly, the analogous reaction with the related amido indolo ester failed to take place, even when the tethered π-bond contained an electron-withdrawing carbomethoxy group. It would seem that the geometric requirements for the intramolecular cycloaddition of the furo[3,4-b]indole system with the tethered π-bond imposes distinct restrictions upon the bond angles ...

Intramolecular Cycloaddition Reactions of Furo[3,4-b]indoles for Alkaloid Synthesis

Model studies dealing with the Cu(II)- or Rh(II)-catalyzed carbenoid cyclization/cycloaddition cascade of several α-diazo indolo amido esters have been carried out as an approach to the alkaloid scandine. The Cu(II)-catalyzed reaction of an α-diazo indolo diester that contains a tethered oxa-pentenyl side chain was found to give rise to a reactive benzo[c]furan which undergoes a subsequent [4 + 2]-cycloaddition across the tethered π-bond. The reaction proceeds by the initial generation of a copper carbenoid intermediate which cyclizes onto the adjacent carbonyl group to give a reactive benzo[c]furan which in certain cases can be isolated. Disappointingly, the analogous reaction with the related amido indolo ester failed to take place, even when the tethered π-bond contained an electron-withdrawing carbomethoxy group. It would seem that the geometric requirements for the intramolecular cycloaddition of the furo[3,4-b]indole system with the tethered π-bond imposes distinct restrictions upon the bond angles of the reacting centers to prevent the cycloaddition reaction from occurring. However, the incorporation of another carbonyl group on the nitrogen atom of the tethered alkenyl diazo amido indolo ester seemingly provides better orbital overlap between the reacting π-systems and allows the desired cycloaddition reaction to occur.

Dimethyl 5-acetyl-1-hy-droxy-4-methyl-1H-pyrrole-2,3-di-carboxyl-ate, an oxidation-resistant N-hy-droxy-pyrrole.

The title compound, C11H13NO6, exhibits an intra­molecular O–H⋯O=C hydrogen bond between the N-hydroxyl H atom and carbonyl O atom of the neighboring acetyl group. This finding contradicts a previously published model in which the hydrogen bond was postulated to occur with the neighboring carbomethoxy group. This relatively strong hydrogen bond [O—H⋯O: D = 2.5583 (11) Å and θ = 152°] may underlie the resistance of the title compound to oxidation into the corresponding nitroxide.

Spectroscopy of Protonated Tetraphenylporphyrins with Amino/Carbomethoxy Substituents: Hyperporphyrin Effects and Evidence for a Monoprotonated Porphyrin

Spectrophotometric titrations for a full series of para-amino/carbomethoxy-substituted tetraphenylporphyrins were carried out using methanesulfonic acid in DMSO to study the hyperporphyrin effect across different substitution patterns. The series included zero, one, two (cis and trans), three, and four amino groups, with the remaining para substituents carbomethoxy groups. With increasing numbers of aminophenyl groups, the relative basicity increased and the hyperporphyrin effect increased, marked by a strong red band and a split Soret band. The cis diamino derivative showed a stronger hyperporphyrin effect compared to the trans isomer, which can be explained based on simple resonance forms. For the monoamino derivative, an initial increase in the Soret band upon acid titration along with well-defined isosbestic points provided evidence for a monoprotonated porphyrin, distinct from the diprotonated and triprotonated states. The relative stability of this unusual intermediate is proposed to be due to charge delocalization of the first cation to the single amino group and destabilization of the second protonation by the electron-withdrawing carbomethoxy substituents.

Cleavage of Ether, Ester, and Tosylate C(sp3)–O Bonds by an Iridium Complex, Initiated by Oxidative Addition of C–H Bonds. Experimental and Computational Studies

A pincer-ligated iridium complex, (PCP)Ir (PCP = κ(3)-C6H3-2,6-[CH2P(t-Bu)2]2), is found to undergo oxidative addition of C(sp(3))-O bonds of methyl esters (CH3-O2CR'), methyl tosylate (CH3-OTs), and certain electron-poor methyl aryl ethers (CH3-OAr). DFT calculations and mechanistic studies indicate that the reactions proceed via oxidative addition of C-H bonds followed by oxygenate migration, rather than by direct C-O addition. Thus, methyl aryl ethers react via addition of the methoxy C-H bond, followed by α-aryloxide migration to give cis-(PCP)Ir(H)(CH2)(OAr), followed by iridium-to-methylidene hydride migration to give (PCP)Ir(CH3)(OAr). Methyl acetate undergoes C-H bond addition at the carbomethoxy group to give (PCP)Ir(H)[κ(2)-CH2OC(O)Me] which then affords (PCP-CH2)Ir(H)(κ(2)-O2CMe) (6-Me) in which the methoxy C-O bond has been cleaved, and the methylene derived from the methoxy group has migrated into the PCP Cipso-Ir bond. Thermolysis of 6-Me ultimately gives (PCP)Ir(CH3)(κ(2)-O2CR), the net product of methoxy group C-O oxidative addition. Reaction of (PCP)Ir with species of the type ROAr, RO2CMe or ROTs, where R possesses β-C-H bonds (e.g., R = ethyl or isopropyl), results in formation of (PCP)Ir(H)(OAr), (PCP)Ir(H)(O2CMe), or (PCP)Ir(H)(OTs), respectively, along with the corresponding olefin or (PCP)Ir(olefin) complex. Like the C-O bond oxidative additions, these reactions also proceed via initial activation of a C-H bond; in this case, C-H addition at the β-position is followed by β-migration of the aryloxide, carboxylate, or tosylate group. Calculations indicate that the β-migration of the carboxylate group proceeds via an unusual six-membered cyclic transition state in which the alkoxy C-O bond is cleaved with no direct participation by the iridium center.

Methyl 2-bromo-3-(4-chlorobenzenesulfonamido)benzoate

In the crystal structure of the title compound, C14H11BrClNO4S, the mol­ecules form inversion dimers with R 2 2(8) motifs through pairs of N—H⋯O hydrogen bonds. The benzene rings are not coplanar and subtend a dihedral angle of 66.27 (8)°. The carbomethoxy group makes a dihedral angle of 75.1 (1)° with the ring to which it is attached.

Easy transformation of indoles to substituted tryptanthrins with powerful AHR activity

Malassezia furfur isolates from diseased skin preferentially biosynthesize compounds which are among the most active known Aryl-hydrocarbon Receptor (AhR) inducers, such as indirubin and tryptanthrin. In our effort to study their production from Malassezia spp., we investigated the role of indole-3-carboxaldehyde (I3A), the most abundant metabolite of Malassezia when grown on tryptophan agar, as a possible starting material for the biosynthesis of both alkaloids. Treatment of I3A with H2O2 and use of diphenyldiselenide as a catalyst resulted in the simultaneous one-step transformation of I3A to indirubin and tryptanthrin in good yields. The same reaction was first applied on simple indole and then on substituted indoles and indole-3-carboxaldehydes, leading to a series of mono- and bi-substituted indirubins and tryptanthrins bearing halogens, alkyl or carbomethoxy groups. Afterwards, they were evaluated for their activity on AhR in four different cell lines stably transfected with a luciferase reporter gene. Among them, 3-bromotryptanthrin interestingly showed 10 times higher activity than dioxin in the human HepG2 7.5 cell line at 6h. In conclusion, I3A could be the starting material used by Malassezia for the production of both indirubin and tryptanthrin through an oxidating mechanism. Additionally, some of the prepared tryptanthrins showed significantly increased activity and selectivity against the human cell line.

Copper(II)-catalyzed ortho-Benzoxylation of 2-Arylpyridines with Sodium Carboxylates

Abstract Copper-catalyzed ortho-benzoxylation of an sp2 C–H bond by sodium carboxylates is described. The procedure tolerates carbomethoxy, formyl, bromo, and chloro groups, providing the benzoxylated products in moderate to good yields.

Synthesis of Biginelli Compounds Using Cobalt Hydrogen Sulfate

AbstractEfficient synthesis of various 2‐oxo(thioxo)‐1,2,3,4‐tetrahydropyrimidines containing acetyl, carboethoxy, carbomethoxy and carboxamide groups on 5‐position of the N1‐substituted and N1‐unsubstituted heterocyclic ring was achieved using cobalt hydrogen sulfate Co(HSO4)2 under thermal conditions. Good to high yield, shorter reaction times, easy work up and simple preparation of Co(HSO4)2 are the advantages using this synthetic method.

Amidation of the ester group of methylpheoforbide a with sterically nonhindered primary and secondary aliphatic amines

It is shown that the reaction of methylpheoforbide a with a series of primary and secondary aliphatic amines at elevated temperature (boiling in toluene) leads to the amidation of carbomethoxy group in the position 13(2) of the methylpheoforbide a exocycle instead of the cleavage of exocycle with the formation of the corresponding 13-amides of the chlorin e6. Possible reasons of the observed change in the reaction pathway are presented.